U.S. application Ser. No. 11/372,992 filed Mar. 10, 2006, which is commonly assigned to the assignee of the present disclosure and included herein by reference in its entirety, is directed at animal chews comprising more than one material wherein the materials may be different in, for instance, hardness, flexural modulus, tensile strength, clarity or composition. The materials may be disposed in layered relationship. The chews may be formed by insert molding, multiple component molding, rotary molding, shuttle molding or any number of melt conversion processes.
U.S. Pat. No. 6,916,497 issued on Jul. 12, 2005 and commonly assigned to the assignee of the present disclosure is also included herein by reference in its entirety. It is directed at a vitamin and/or mineral and/or herbal enriched molded animal chew toy. The vitamins, minerals and/or herbal additives may be incorporated into the molded chew toy under conditions that minimize thermal degradation of such additives, such as by the inclusion of water during processing. The chew toy may be formed by combining resin, water and one or a plurality of said vitamins and/or minerals and/or herbs to form a mixture. The resin may include any and all resins that can be made to flow under conditions of elevated temperature and can be molded and cooled into a desired shape. Resins therefore include natural and/or synthetic macromolecules or polymeric type structures, including thermoplastic polymers, starch, casein, denatured and partially hydrolyzed collagen and mixtures thereof.
U.S. application Ser. No. 11/747,132 filed May 10, 2007, and which is commonly assigned to the assignee of the present disclosure and included herein by reference in its entirety is directed at a method of manufacturing a multi-component pet treat or chew comprising two or more materials which may differ in some physical, optical, nutritional, sensual or compositional property, wherein the multiplicity of materials may be formed to lie adjacent one another in layered, surrounding, partially surrounding, abutting or interlocked fashion. This application is focused upon the injection molding process.
The prior art discloses various processes and compositions for enhancing the palatability of pet foods, however, it will be appreciated by those skilled in the art that a need continues to exist for improved methods and compositions which will allow both pet foods and pet chews to deliver the vitamins, minerals and other nutritional additives that may normally be degraded during the manufacture of such extruded pet products.
A more cost efficient process may be to simultaneously extrude multiple compositions, combine such in an extrusion die and then cut the extrudate to length to form various shapes as pet chews having discrete sections of shape and composition. Operating separate extruders for each composition may allow one to tailor the processing conditions to allow such ingredients as herbs, minerals, vitamins and natural colorants to be processed under conditions that minimize their heat and/or shear history and reduce thermal degradation.